diff --git a/packages/ludic.render3d/env.ludic b/packages/ludic.render3d/env.ludic
index be8e2417..e5d2d485 100644
--- a/packages/ludic.render3d/env.ludic
+++ b/packages/ludic.render3d/env.ludic
@@ -382,6 +382,11 @@ export state Render3dState {
   gvk_buf_size: []int = null
   gvk_buf_map: []pointer = null      # host-visible buffers stay mapped for their whole life
   gvk_buf_used: []int = null         # the frame (gvk_frame_no) a draw last bound the buffer in
+  gvk_bsp_buf: []long = null         # per handle, a second buffer a re-filled one swaps with (gvk_buf_reserve)
+  gvk_bsp_mem: []long = null
+  gvk_bsp_size: []int = null
+  gvk_bsp_map: []pointer = null
+  gvk_bsp_used: []int = null
   gvk_frame_no: int = 1
   @max(4096) gvk_retired_buf: []long = null
   @max(4096) gvk_retired_mem: []long = null
diff --git a/packages/ludic.render3d/gpu_vk_res.ludic b/packages/ludic.render3d/gpu_vk_res.ludic
index 94b27e96..efa903eb 100644
--- a/packages/ludic.render3d/gpu_vk_res.ludic
+++ b/packages/ludic.render3d/gpu_vk_res.ludic
@@ -643,8 +643,11 @@ function gvk_buf_new(render3d_st: mut Render3dState) -> int {
   if render3d_st.gvk_buf == null {
     render3d_st.gvk_buf = new []long;  render3d_st.gvk_buf_mem = new []long;  render3d_st.gvk_buf_size = new []int;  render3d_st.gvk_buf_map = new []pointer
     render3d_st.gvk_buf_used = new []int;  render3d_st.gvk_retired_buf = new []long;  render3d_st.gvk_retired_mem = new []long
+    render3d_st.gvk_bsp_buf = new []long;  render3d_st.gvk_bsp_mem = new []long;  render3d_st.gvk_bsp_size = new []int
+    render3d_st.gvk_bsp_map = new []pointer;  render3d_st.gvk_bsp_used = new []int
     # handle 0 is "no buffer", as it is on OpenGL
     push(render3d_st.gvk_buf, zero);  push(render3d_st.gvk_buf_mem, zero);  push(render3d_st.gvk_buf_size, 0);  push(render3d_st.gvk_buf_map, null);  push(render3d_st.gvk_buf_used, 0)
+    gvk_bsp_grow(render3d_st)
   }
   # a handle a deleted buffer gave back first (gvk_buf_delete)
   if render3d_st.gvk_buf_spare != null and len(render3d_st.gvk_buf_spare) > 0 {
@@ -654,6 +657,7 @@ function gvk_buf_new(render3d_st: mut Render3dState) -> int {
     return b
   }
   push(render3d_st.gvk_buf, zero);  push(render3d_st.gvk_buf_mem, zero);  push(render3d_st.gvk_buf_size, 0);  push(render3d_st.gvk_buf_map, null);  push(render3d_st.gvk_buf_used, 0)
+  gvk_bsp_grow(render3d_st)
   return len(render3d_st.gvk_buf) - 1
 }
 
@@ -670,6 +674,7 @@ function gvk_buf_delete(render3d_st: mut Render3dState, b: int) -> void {
 }
 
 function gvk_buf_release(render3d_st: mut Render3dState, b: int) -> void {
+  gvk_bsp_drop(render3d_st, b)
   if render3d_st.gvk_buf[b] == 0 { return }
   let zero: long = 0
   if gvk_buf_busy(render3d_st, b) {
@@ -740,7 +745,15 @@ function gvk_buf_reserve(render3d_st: mut Render3dState, b: int, n: int) -> bool
   if b <= 0 or b >= len(render3d_st.gvk_buf) { return false }
   # already big enough, and no draw this frame reads what is there: fill it in place
   if render3d_st.gvk_buf[b] != 0 and render3d_st.gvk_buf_size[b] >= n and (not gvk_buf_busy(render3d_st, b) or gvk_buf_is_gpu(render3d_st, b)) { return true }
-  gvk_buf_release(render3d_st, b)
+  # big enough but read by a frame still on the GPU: its second buffer, when that one is free, and
+  # else the busy one becomes the second and a new one is made - a buffer re-filled every frame (the
+  # interface's vertices) ping-pongs between two, where it was made and destroyed every frame
+  if render3d_st.gvk_buf[b] != 0 and render3d_st.gvk_buf_size[b] >= n {
+    if gvk_bsp_swap(render3d_st, b, n) { return true }
+    gvk_bsp_park(render3d_st, b)
+  } else {
+    gvk_buf_release(render3d_st, b)
+  }
   var size = n
   if size < 64 { size = 64 }
   let size_l: long = size
@@ -853,3 +866,65 @@ function gvk_prime_tables(render3d_st: mut Render3dState) -> void {
   let none: long = 0
   for i in 0 .. GVK_PRIME_MAX { push(hs, none) }
 }
+
+# ---- a re-filled buffer's second: gvk_buf_reserve swaps to it while the first is still being read ----
+@alloc_ok("one slot per buffer handle, beside the handle's own (gvk_buf_new)")
+function gvk_bsp_grow(render3d_st: mut Render3dState) -> void {
+  let zero: long = 0
+  push(render3d_st.gvk_bsp_buf, zero)
+  push(render3d_st.gvk_bsp_mem, zero)
+  push(render3d_st.gvk_bsp_size, 0)
+  push(render3d_st.gvk_bsp_map, null)
+  push(render3d_st.gvk_bsp_used, 0)
+}
+function gvk_bsp_busy(render3d_st: Render3dState, b: int) -> bool {
+  let u = render3d_st.gvk_bsp_used[b]
+  return u == render3d_st.gvk_frame_no or (render3d_st.gvk_frame_pending and u == render3d_st.gvk_frame_pending_no)
+}
+# the second in place of the first when it is there, big enough and read by nothing still running
+function gvk_bsp_swap(render3d_st: mut Render3dState, b: int, n: int) -> bool {
+  if render3d_st.gvk_bsp_buf == null or b >= len(render3d_st.gvk_bsp_buf) { return false }
+  if render3d_st.gvk_bsp_buf[b] == 0 or render3d_st.gvk_bsp_size[b] < n or gvk_bsp_busy(render3d_st, b) { return false }
+  let tb = render3d_st.gvk_buf[b]
+  let tm = render3d_st.gvk_buf_mem[b]
+  let ts = render3d_st.gvk_buf_size[b]
+  let tp = render3d_st.gvk_buf_map[b]
+  let tu = render3d_st.gvk_buf_used[b]
+  render3d_st.gvk_buf[b] = render3d_st.gvk_bsp_buf[b];  render3d_st.gvk_buf_mem[b] = render3d_st.gvk_bsp_mem[b]
+  render3d_st.gvk_buf_size[b] = render3d_st.gvk_bsp_size[b];  render3d_st.gvk_buf_map[b] = render3d_st.gvk_bsp_map[b]
+  render3d_st.gvk_buf_used[b] = render3d_st.gvk_bsp_used[b]
+  render3d_st.gvk_bsp_buf[b] = tb;  render3d_st.gvk_bsp_mem[b] = tm;  render3d_st.gvk_bsp_size[b] = ts
+  render3d_st.gvk_bsp_map[b] = tp;  render3d_st.gvk_bsp_used[b] = tu
+  return true
+}
+# the busy first becomes the second (the old second let go), leaving the handle empty for a new one
+function gvk_bsp_park(render3d_st: mut Render3dState, b: int) -> void {
+  let zero: long = 0
+  gvk_bsp_drop(render3d_st, b)
+  render3d_st.gvk_bsp_buf[b] = render3d_st.gvk_buf[b];  render3d_st.gvk_bsp_mem[b] = render3d_st.gvk_buf_mem[b]
+  render3d_st.gvk_bsp_size[b] = render3d_st.gvk_buf_size[b];  render3d_st.gvk_bsp_map[b] = render3d_st.gvk_buf_map[b]
+  render3d_st.gvk_bsp_used[b] = render3d_st.gvk_buf_used[b]
+  render3d_st.gvk_buf[b] = zero;  render3d_st.gvk_buf_mem[b] = zero;  render3d_st.gvk_buf_size[b] = 0
+  render3d_st.gvk_buf_map[b] = null;  render3d_st.gvk_buf_used[b] = 0
+}
+# the second let go: destroyed now, or retired until the frame that read it has finished
+function gvk_bsp_drop(render3d_st: mut Render3dState, b: int) -> void {
+  if render3d_st.gvk_bsp_buf == null or b >= len(render3d_st.gvk_bsp_buf) or render3d_st.gvk_bsp_buf[b] == 0 { return }
+  let zero: long = 0
+  if gvk_bsp_busy(render3d_st, b) {
+    @alloc_ok("within the retire lists' room made at start-up (@max 4096)")
+    push(render3d_st.gvk_retired_buf, render3d_st.gvk_bsp_buf[b])
+    @alloc_ok("within the retire lists' room made at start-up (@max 4096)")
+    push(render3d_st.gvk_retired_mem, render3d_st.gvk_bsp_mem[b])
+    @alloc_ok("within the retire lists' room made at start-up (@max 4096)")
+    while len(render3d_st.gvk_retired_frame) < len(render3d_st.gvk_retired_buf) - 1 { push(render3d_st.gvk_retired_frame, 0) }
+    @alloc_ok("within the retire lists' room made at start-up (@max 4096)")
+    push(render3d_st.gvk_retired_frame, render3d_st.gvk_bsp_used[b])
+  } else {
+    render3d_st.gvk_mk_x_buf += 1
+    Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_bsp_buf[b], render3d_st.gvk_ac)
+    gvk_mem_free(render3d_st, gvk_mem_id(render3d_st.gvk_bsp_mem[b]))
+  }
+  render3d_st.gvk_bsp_buf[b] = zero;  render3d_st.gvk_bsp_mem[b] = zero;  render3d_st.gvk_bsp_size[b] = 0
+  render3d_st.gvk_bsp_map[b] = null;  render3d_st.gvk_bsp_used[b] = 0
+}
diff --git a/packages/ludic.render3d/overlay.ludic b/packages/ludic.render3d/overlay.ludic
index f9c4ec1d..31e35b65 100644
--- a/packages/ludic.render3d/overlay.ludic
+++ b/packages/ludic.render3d/overlay.ludic
@@ -67,6 +67,29 @@ function overlay_init(render3d_st: mut Render3dState, font_dir: string) -> bool
   return true
 }
 
+# The atlas is white glyphs on alpha, and the overlay reads only the coverage: it is kept as one
+# byte a texel (R8). As RGBA a 3072 x 2688 atlas was 44 MB with its mips, the most of any UI texture.
+@alloc_ok("loading a font: a load, not a frame")
+function ov_font_tex(render3d_st: mut Render3dState, path: string) -> int {
+  let px = png_decode(render3d_st, path)
+  if px == null { return 0 }
+  if render3d_st.tex_channels != 4 or render3d_st.tex_depth != 8 {
+    let id0 = tex_upload(render3d_st, px, false, true)
+    free(px)
+    tex_note_size(render3d_st, id0)
+    return id0
+  }
+  let n = render3d_st.tex_w * render3d_st.tex_h
+  let a = bytes(n)
+  for i in 0 .. n { a[i] = px[i * 4 + 3] }
+  free(px)
+  render3d_st.tex_channels = 1
+  let id = tex_upload(render3d_st, a, false, true)
+  free(a)
+  tex_note_size(render3d_st, id)
+  return id
+}
+
 # Load (or swap to) the font atlas in `font_dir`: font.png and font.json. A game calls it
 # again to change fonts at run time - a language whose script the default atlas does not
 # carry brings its own. Returns false, and keeps the font it had, if there is none there.
@@ -74,7 +97,7 @@ function overlay_init(render3d_st: mut Render3dState, font_dir: string) -> bool
 function overlay_font(render3d_st: mut Render3dState, font_dir: string) -> bool {
   let meta = Fs.read_text(font_dir + "/font.json")
   if meta == null { return false }
-  let tex = tex_load_ex(render3d_st, font_dir + "/font.png", false, 0)
+  let tex = ov_font_tex(render3d_st, font_dir + "/font.png")
   if tex == 0 { return false }
   let j = Json.parse(meta)
   render3d_st.ov_font_cols = jint(j, "cols", 16);  render3d_st.ov_font_rows = jint(j, "rows", 6)
diff --git a/packages/ludic.render3d/shaders/overlay.frag b/packages/ludic.render3d/shaders/overlay.frag
index 1b3d08f9..0d3a9c30 100644
--- a/packages/ludic.render3d/shaders/overlay.frag
+++ b/packages/ludic.render3d/shaders/overlay.frag
@@ -1,4 +1,4 @@
-// 2D overlay: an image texture, the font atlas (white glyphs on alpha) or a flat colour, times a
+// 2D overlay: an image texture, the font atlas (glyph coverage, R8) or a flat colour, times a
 // colour. Which one is the vertex's own: v carries 4 x the mode (0 image, 1 font, 2 flat) on top of
 // its real coordinate, so text, panels and an image's quads share a draw (overlay.ludic, ov_use_tex).
 in vec2 v_uv;
@@ -27,7 +27,7 @@ void main() {
   if (mode > 1.5) {
     o_color = v_col;
   } else if (mode > 0.5) {
-    o_color = vec4(v_col.rgb, v_col.a * texture(u_font, uv).a);
+    o_color = vec4(v_col.rgb, v_col.a * texture(u_font, uv).r);   // the atlas is its coverage alone (R8)
   } else {
     vec4 t = texture(u_tex, uv);
     o_color = vec4(v_col.rgb * t.rgb, v_col.a * t.a);
diff --git a/packages/ludic.render3d/shaders/spv/1b654972.frag.spv b/packages/ludic.render3d/shaders/spv/1b654972.frag.spv
index 2c38afa0..46c181f1 100644
Binary files a/packages/ludic.render3d/shaders/spv/1b654972.frag.spv and b/packages/ludic.render3d/shaders/spv/1b654972.frag.spv differ
diff --git a/packages/ludic.render3d/shaders/spv/e86f78e8.frag.spv b/packages/ludic.render3d/shaders/spv/e86f78e8.frag.spv
index eedac340..5cc0f51d 100644
Binary files a/packages/ludic.render3d/shaders/spv/e86f78e8.frag.spv and b/packages/ludic.render3d/shaders/spv/e86f78e8.frag.spv differ